1. Field of the Invention
The present invention relates to an apparatus and method for driving a plasma display panel. More specifically, the present invention relates to a sustain discharge circuit for plasma display panels.
2. Description of the Related Art
A plasma display panel (PDP) is a flat panel display that uses plasma generated by gas discharge to display characters or images. The PDP includes, according to its size, more than several scores to millions of pixels arranged in a matrix pattern. Such a PDP is classified as a direct current (DC) type or an alternating current (AC) type according to its discharge cell structure and the waveform of the driving voltage applied thereto.
The DC PDP has electrodes exposed to a discharge space to allow DC to flow through the discharge space while voltage is applied, and thus requires a certain resistance for limiting the current. Contrarily, the AC PDP has electrodes covered with a dielectric layer that naturally forms a capacitance component to limit the current and to protect the electrodes from the impact of ions during a discharge, and has longevity superior to the DC PDP.
A driving method of the AC PDP includes a reset step, an addressing step, a sustain discharge step, and an erase step.
In the reset step, each cell is initialized to be ready to perform an addressing operation on the cell. In the addressing step, wall charges are formed on selected “on”-state cells (i.e., addressed cells) in the panel. In the sustain step, a discharge occurs to actually display an image on the addressed cells. In the erase step, the wall charges on the cells are erased to end the sustain discharge.
In the AC PDP, the scan and sustain electrodes for sustain discharge act as a capacitative load to form a capacitance between the scan and sustain electrodes, which is equivalently denoted as a “panel capacitor” hereinafter. Kishi et al. suggested a circuit (Japanese Patent No. 3,201,603) that applies a waveform for a sustain discharge on the scan and sustain electrodes.
In conventional circuits, however, a sustain discharge pulse swinging between positive (+) voltage Vs and negative (−) voltage −Vs is applied to the scan and sustain electrodes. With the sustain discharge pulse applied to the scan electrode and the sustain electrode for phase inversion of each other, the potential difference between the scan electrode and the sustain electrode reaches a voltage of 2Vs required for a sustain discharge. Individual elements used in this circuit must have a withstand voltage of Vs, so that any element having a low withstand voltage can be used. Such a conventional circuit, however, uses a pulse swinging from −Vs to Vs, and it cannot be used for a plasma display panel that uses a sustain discharge pulse with no negative (−) voltage.